Recently, there has been considerable interest in radar processing systems using arbitrary, both deterministic and non-deterministic, waveforms over a wide spectrum of applications, such as through wall surveillance, detection, tracking, Doppler estimation, polarimetry, interferometry, ground-penetrating or subsurface profiling, synthetic aperture radar (SAR) imaging, inverse synthetic aperture radar (ISAR) imaging, foliage penetration imaging, etc. This is because of that the technology for the generation of arbitrary waveforms has matured by the introduction of digitally controlled waveform generators. One of the major advantages of using arbitrary waveforms is its inherent immunity from jamming, detection, and external interference.
A noise radar, which is an example of a radar using arbitrary waveforms, is a form of random waveform radar whose transmitting waveform is a microwave noise source or is modulated by a lower frequency white noise source in contrast to the conventional pulse, CW (continuous wave), FM (frequency modulated), or FM/CW radars. Because of the truly random or pseudo random transmitting waveform, noise radars have many advantages compared with conventional radars, including unambiguous measurement of range and Doppler estimations, high immunity to noise, very low probability of intercept (LPI), high electro-magnetic compatibility, good electronic counter countermeasure (ECCM) capability, good counter electronic support measure (CESM) capability, and ideal ‘thumbtack’ ambiguity function.
However, despite these many advantages the research on radar processing systems using arbitrary waveforms has shown very little progress, since it was first suggested and researched upon in the 1960's. An existing problem with the implementation of radar processing systems using arbitrary waveforms is still, the limited availability and the cost of suitable electronic components capable of handling the high computational loads.